EPA Method 26
Hydrogen Chloride, Halides & Halogens
Method Overview
- • Non-isokinetic constant rate sampling.
- • Filter separates particulate halides from gaseous halides.
- • Usually only the gaseous halides are analyzed.
- • Analysis by HPLC/IC.
Target Compounds
- • Hydrochloric acid
- • Hydrogen fluoride
- • Hydrogen bromide
- • Chlorine (Cl2)
- • Bromine (Br2)
- • Also: Nitrate, Sulfite, phosphate
- • Not approved for fluorine (F2)
Method Summary
- • Charge 1st 2 impingers with 200 mL 0.1N H2SO4. Charge 3rd
and 4th impingers with 0.1N NaOH. Charge 5th impinger with silica
gel.
- • Filter holder must be Teflon
- • Acid gases, HCl, HF, HBr are soluble in H2SO4 and are collected
in the first few impingers. Chlorine (Cl2) and bromine (Br2) are
not soluble in the acid impingers and pass through to be collected
in the basic impingers ( NaOH)
- • If water droplets are expected, use of a cyclone is recommended.
If used, a clean air purge should be done after the run until the
contents of the cyclone evaporate to dryness.
- • If high moisture is expected, an optional 1st impinger
may be added with a short stem. Put 50 mL of 0.1N H2SO4 in the optional
impinger to acidify the contents.
- • When Cl2 or Br2 are analytes, add sodium thiosulfate to
the NaOH reagent after the run, which will convert hypohalous species
back to Cl- or Br- for proper analytical quanitation.
Quality Assurance
- • Water blank.
- • Reagent blank.
- • HCl audits are available to agencies.
- • Enthalpy will provide separate analytical curves for the
acid and base fractions, with each curve generated in the same matrix
as the sample. 4 standards are analyzed in duplicate before and
after the analysis.
Shipping Tips
- • H2SO4 and NaOH are hazardous and should be shipped as Hazardous
Goods. (Call us for the IATA codes as required.)
- • Reagents need not be shipped cold.
- • Important - include a complete Chain of Custody form for
EACH shipping container. (See our downloads section for a COC form.)
Enthalpy Experience
- • Enthalpy has analyzed M26 and M26A fractions for ~6 years,
and during that time we have never failed an EPA audit for M26.
- • A more extensive compound list is available for engineering
tests, albeit not approved for compliance.
- • Sulfate is a problem for the analysis and can sometimes,
though not always, be removed by addition of BaCl2.
- • Enthalpy operates an Alltech suppression system that increases
the sensitivity of the analysis. When sulfate is a problem, the
increased instrument sensitivity allows us to dilute the samples
to minimize sulfate while maintaining acceptable detection limits.
